Jenna (left) and Barbara Bush listen to their father at the concert in Washington. (Reuters)

Washington, Jan. 19 (Reuters): President George W. Bush told US troops today that 'much more will be asked of you' in Iraq and elsewhere as three days of ceremonies marking his inauguration got off to a sombre beginning.

Bush is to be sworn in for a second four-year term at midday tomorrow on Capitol Hill and thousands of Republicans were flocking to Washington for the celebrations under extremely heavy security.

Police scrambled to handle an emergency a block away from the White House and near the planned route for the inaugural parade. Police surrounded a man in a van who claimed to have 57 litres of fuel and threatened to blow it up if he did not get his child back, the FBI said.

'It's domestic, not terrorism,' said an FBI spokeswoman.

Bush, vice-president Dick Cheney and defence secretary Donald Rumsfeld went to the MCI Center in Washington for an event called 'Saluting Those Who Serve' that honoured war veterans and the valour of the fallen in conflicts from the Revolutionary War to Iraq.

Among the 7,000 people in the audience were troops wounded in combat, 75 family members of soldiers killed in Iraq and Afghanistan and as many as 80 winners of the Congressional Medal of Honor, the highest military award. The event was beamed to troop gatherings in Iraq and Afghanistan.

Bush told the troops that 'much more will be asked of you in the months and years ahead.'

'In Afghanistan and Iraq, the liberty that has been won at great cost now must be secured. We still face terrorist enemies who wish to harm our people, and are seeking weapons that would allow them to kill on an unprecedented scale. These enemies must be stopped, and you are the ones who will stop them.'

The event included a number of tearful moments such as when Bush's father, former President George Bush, read a letter he had written to his family after surviving the shooting down of his warplane by Japanese guns in 1944.

The decision to have the first official inaugural event honouring war veterans and those killed in war reflected the nature of Bush's first term, which was dominated by conflicts in Iraq and Afghanistan.

Reflecting a theme for his inaugural address tomorrow, Bush said: 'The promise of liberty is spreading across the world' and cited Iraq's scheduled January 30 elections.

Later, Bush hailed the spirit of volunteerism by attending a youth concert with the theme: 'America's Future Rocks Today ' A Call to Service.'. A Washington Post/ABC News poll said 45 per cent of those surveyed would prefer the country go in the direction Bush wanted to lead it, while 39 per cent said Democrats should lead the way.